The present invention relates to a saw assembly for a grip-harvester, comprising a stand; a bar; a saw chain running around the bar and a chain sprocket; a bar holder pivotably journalled on the stand; a saw motor driving the chain sprocket; and a feeding-out and feeding-in device for feeding the bar out and in to perform a sawing operation, said feeding-out and feeding-in device comprising a hydraulic cylinder mounted on the stand and having a piston rod, and connection means to transmit the movements of the piston rod to the pivotable bar holder.
In previously used saw assemblies of the type described in the introduction the mechanical connection for transmitting the movement of the hydraulic cylinder to the bar holder is constructed of movable parts and these can therefore be subjected to external influence causing damage to the connection, or snow and ice may collect around the connection thus deteriorating or completely destroying its function. In certain cases special guides are also required for the piston rod, to take up the radial forces this is subjected to during said transmission of movement. The known saw assemblies have no efficient device for sensing and recording the angular position and direction of movement of the saw bar in relation to its home position. Without such efficient device it is impossible to arrange an efficient marking system to colour-mark a sawn cut surface, for instance, in conjunction with the actual sawing operation.
The object of the present invention is to considerably reduce the problems mentioned above and provide a simplified saw assembly which lacks movable parts between the piston rod and the element which is caused to rotate and comprises the bar holder, and which saw assembly can be provided with an efficient device for sensing and recording angular position and direction of movement of the saw bar so it is also possible to make use of an efficient marking system. This is enabled while still retaining the dimensions of the saw assembly, or even with reduced dimensions.
The saw assembly according to the invention is characterized in that said connection means comprises a toothed wheel pivotably journalled in the stand, which toothed wheel is coaxially, rigidly joined to the bar holder and is provided with a toothed wheel rim or a sector of a toothed wheel rim situated on a level with and facing the piston rod, in that the piston rod is in the form of a rack with teeth facing the toothed wheel and in engagement with the teeth on the rim or the rim sector, in that the saw assembly comprises a device for sensing and recording the angular position of the saw bar in relation to an initial position, which device comprises a toothed wheel in toothed engagement with the toothed wheel of the feeding-out and feeding-in device and is smaller than the toothed wheel so that a gear ratio &gt;1 is obtained between the larger toothed wheel and the smaller toothed wheel, and also a sensor which, in an initial position of the saw bar, is situated immediately opposite a gap between two teeth or immediately opposite a tooth in said smaller toothed wheel.